The present invention relates generally to apparatus and methods for making pre-assembled or pre-fastened absorbent undergarments, and more particularly to apparatus and methods for engaging cooperating fastening components of pre-fastened absorbent undergarments during the making of such undergarments.
Absorbent undergarments have numerous applications including, without limitation, diapers, training pants and adult incontinence products. A typical absorbent undergarment is formed as a composite structure including an absorbent assembly disposed between a liquid permeable bodyside liner and an outer cover. These components can be combined with other materials and features such as elastic materials and containment structures to form a product which is specifically suited to its intended purposes. A number of such undergarments include fastening components which are intended to be secured together (e.g., pre-fastened) during manufacture of the garment so that the product is packaged in it's fully assembled, ready-to-wear form.
As an example, a child's training pants conventionally has a central absorbent chassis and front and back side panels extending laterally out from the chassis adjacent longitudinally opposite ends thereof. Each of the front and back side panels has a fastening component thereon, such as a hook or a loop fastener. During manufacture of the training pants, the central absorbent chassis is initially formed generally flat and then folded over so that the front and back side panels face each other. The respective fastening components of the front and back side panels are then aligned and engaged with each other to pre-fasten the training pants in its fully assembled three-dimensional form.
However, existing techniques for making conventional absorbent undergarments such as the training pants described above or other pre-fastened undergarments in which fastening components are pre-fastened together during manufacture are in some respects inadequate. In particular, typical manufacturing processes are performed at high speeds, such as to make 250 or more pre-fastened absorbent undergarments per minute. One sometimes limiting factor is that folding of the undergarment while the garment is being moved along the machine direction at high speed requires reciprocating movement of a folding device in a direction orthogonal to the direction in which the undergarment web is moving. This can result in inconsistent locating of the fold line along which the garment is folded. Commonly used processes also require multiple stations along the manufacturing apparatus, such as one station at which the garment is folded and a separate station at which the side panels are subsequently fastened together. Specifically, multiple stations must be used so as to avoid any of the folding and engaging devices of the manufacturing line from becoming disposed within the interior of the pre-fastened garment, thereby inhibiting further movement of the garment along the line.
To this end, Japanese Laid-Open Patent Application No. 7-205943 discloses a folding device in which multiple pairs of suction folding means are provided on a rotating drum, with each pair of suction folding means being capable of both folding one absorbent garment and attaching the side edges of the garment together. In particular, as the drum rotates a respective pair of the suction folding means is in an open configuration in which the folding means are laid flat, or tangent relative to the rotating drum. In this configuration, a garment that has been cut from a web of such garments is suctioned flat onto the pair of suction folding means. Upon further rotation of the drum, adhesive is applied to the side edges of the garment. Further rotation of the drum causes the pair of suction folding means to fold inward toward each other while the garment is still suctioned to the respective folding means. The garment is thus folded in half to bring the ends of the garment together. The edges of the garment contact each other such that the adhesive holds the edges together in what is commonly referred to as a butt-seam. Finally, the drum is rotated to a position in which the suction folding means are opened again, whereby suction to one of the folding means is decreased so that the folded garment is held only by the other folding means and then transferred to a conveyor for further processing.
While such a folding device is intended to increase the processing speed for making folded garments, butt-seams are generally undesirable because they present an unfinished appearance. More desirable is what is commonly referred to as a lap seam in which the side edges of the garment at one end thereof overlap and are engaged with the side edges of the garment at the opposite end of the garment. For example, U.S. Pat. No. 5,779,831 discloses an apparatus that grips an unfolded undergarment in four locations and folds the undergarment in half. The gripped portions of the undergarment are then folded inward toward each other. As a result, portions of the undergarment adjacent to the gripped portions overlap each other and are bonded together by an ultrasonic bonding device. However, the portions of the undergarment that are to be bonded together are ungripped (i.e., the overlapping portions adjacent the gripped portions) and are therefore not positively held in opposed relationship. There is a risk that motion of the apparatus or other surrounding conditions can cause the portions that are to be bonded to become misaligned, folded or the like and result in a less than desireable bonding.
Also, while various other apparatus and processes for forming lap seams are known to those skilled in the art, such apparatus and processes typically require the lap seam forming to be conducted other than at the same station at which the folding of the garment occurs. As such, additional processing apparatus and time is needed to make such a lap seam.